Trying to mod a 6V item to run off usb! (Need some advice and help)

yamahahornist · Jan 5, 2016

So I got these (http://www.thinkgeek.com/product/147f/?srp=11) Radioactive Elements Glowing Coaster Set for Christmas but the batteries die in them after 4 hours of use! That's like nothing! I game way longer than that sometimes. So I thought I would solder a usb cable to the pcb and try that. Well no luck :C the leds wouldn't turn on. So I know the coasters run at 6V and usb outputs 5V, so I am thinking thats my problem here?? Any advice guys?? Is there anything I could do?? Anyway to run these usb??? Oh also the Pcb has two (-) spots and one (+) slot. I just soldered the red (+) cable to the + and the black to the - ( i tried both (-) spots).

Oh and I also soldered the battery pack back on and it still works, so I didnt break it

getochkn · Jan 5, 2016

Are you sure they run at 6V? How were the batteries wired inside? Would have to be 4 in series x 2 set in parallel. It shouldn't matter, the LED's should light up just a bit more dim at 5v over 6v. I have LED candles that take 3x1.5AAA, so 4.5v and work fine off USB. You can always overdrive/underdrive a LED a bit.

shiitaki · Jan 5, 2016

Inside your computer you have multiple voltages. If you were to take a molex connector and added diodes in a string so that the combined forward voltage drop is about a volt, you can connect between the red and yellow colored wires that are present in a molex connector. An extra adapter that often comes with case fans would be good for this. 12 volts-5volts=7 volts, minus 1volt in diodes gives you the 6 volts. What is great about this is that your power supply will regulate the voltage, and it will turn on and off with the rest of your computer. Will even be off when you computer is sleeping. I do the seven volt thing to quite noisy fans and it has never caused me an issue. Just don't make any other connections with the computer other than the red and yellow, because case ground will be different than ground for your device. I assume it is plastic housed and so this should be a problem. I hope you have a volt meter to check polarity before plugging in, sound like something you would have. How many batteries does it take? If it is more than 4 then you shouldn't even need the diode.

IF you do use a fan adapter, you can simply move the black pin over, but then you can't connect anything else after it.

To get 6 volts from 5 volt USB is possible, but not practical.

yamahahornist · Jan 5, 2016

getochkn :

http://i1068.photobucket.com/albums/u453/Ericarthurc/IMG_0241_zpstnfztco3.jpg

http://i1068.photobucket.com/albums/u453/Ericarthurc/IMG_0240_zps9dfmkwiv.jpg

Here's a look at how it works. grey wire into (-), red into (-), and black into (-)

it uses 2 CR2032 V3 batteries

getochkn · Jan 5, 2016

CAn't figure out exactly how it's wired or why it's that why. 6v worth of lights should still lightup on 5v of power. It's enough forward voltage to start them so unless it's 3V, which makes more sense. Seems there are what 4LED's, so 2 in parallel per 2 LED.

yamahahornist · Jan 5, 2016

I actually got it to work!!! I realized that there is a little magnet in the back plate of the device that when pushed down causes the circuit to be completed. Once I pushed it down it started to glow blue!

DDD thanks for all the help

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Trying to mod a 6V item to run off usb! (Need some advice and help)

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